I did use conventional horns -shortened-, not the proper type for linking biplane ailerons.
BTW, I saw some "biplane aileron linking" horns in one of our LHSs the other day. They were something like $5 a PAIR. (... a PAIR ???
) and after looking at them awhile it dawned on me. They didn't mention a very important detail about them on the package. They really should both go on the same side of the surface depending on the wing stagger. They both ought to be on the top of the aileron if the biplane stagger was top wing forward, and a Staggerwing oughta have them on the bottoms. And truth is, it's dead simple and cheap to make "horns" for these aileron connections. And they're better and stronger and lighter. And the components are probably lying in your scrap box "in disguise", so the cost actually would be moot.